Tuning the Driving Force for Charge Transfer in Perovskite-Chromophore Systems

Understanding the interplay between the kinetics andenergeticsof photophysical processes in perovskite-chromophore hybridsystems is crucial for realizing their potential in optoelectronics,photocatalysis, and light-harvesting applications. By combining steady-stateoptical characterizations and transient absorption spectroscopy, wehave investigated the mechanism of interfacial charge transfer (CT)between colloidal CsPbBr3 nanoplatelets (NPLs) and surface-anchoredperylene derivatives and have explored the possibility of controllingthe CT rate by tuning the driving force. The CT driving force wastuned systematically by attaching acceptors with different electronaffinities and by varying the bandgap of NPLs via thickness-controlledquantum confinement. Our data show that the charge-separated stateis formed by selectively exciting either the electron donors or acceptorsin the same system. Upon exciting attached acceptors, hole transferfrom perylene derivatives to CsPbBr3 NPLs takes place ona picosecond time scale, showing an energetic behavior in line withthe Marcus normal regime. Interestingly, such energetic behavior isabsent upon exciting the electron donor, suggesting that the dominantCT mechanism is energy transfer followed by ultrafast hole transfer.Our findings not only elucidate the photophysics of perovskite-moleculesystems but also provide guidelines for tailoring such hybrid systemsfor specific applications.

Automated summary

Understanding the kinetics and energetics of photophysical processes in perovskite-chromophore hybrid systems is crucial for their applications in optoelectronics, photocatalysis, and light-harvesting. By investigating the charge transfer mechanism between CsPbBr3 nanoplatelets and surface-anchored perylene derivatives, we have shown that the CT rate can be controlled by tuning the CT driving force. Our findings provide insights into the photophysics of perovskite-molecule systems and offer guidelines for tailoring these hybrid systems for specific applications.